hey everyone i was just wondering if it was possible to combine 2 amps for one sub. im getting a rockford fosgate power hx2 10" sub which is 1000 rms 2000 watts max. And i have 2 amps to use and im not wanting to spend much more money. Ive got a 800 watt RF amp and a 760 watt sony amp. So can i connect the two together get the gains set on each and then connect the positive wire to one amp and the negative wire which combines the two amps outputs into one? or can i go like a positive and a negative from each and connect those into one big positve and one big negative?I know something like this is possible i just want reassurance i guess on what i am doing. BTW its a dual Voice coil sub and both amps are 2 channel. Thanks for any help!


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84 Fiero

you CAN do it...but without the right equipment to perfectly match each amp, your gonna kill your sub.

I would not suggest it unless you know what your doing.


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I have two identical 280 watt pheonix gold amps running a 10w6 (dvc). I wouldn't suggest it if your running a sony and rockford amp though.
The way I set it up was to power each voice coil with it's own amp. But before I did that, I disconnected all other speakers, disabled the crossover on the deck, got a bass cd and set it to a track that repeated a frequency of 100 hz, and turned the volume on my deck up to about 90%. Then i tested the voltage across the negative and positive output terminals from one amp. (oh yeah, make sure the sub isn't connected to the amp while you do this) Then i tested the second amp's voltage and adjusted the gain on both until they were at 15.00 Volts. (use a fluke multimeter)
This is only a good idea if you have two of the exact same amps. I don't think there's a good way of doing it otherwise. You'll end up destorying your equipment and only having to buy new stuff in the end. Might as well spend the money now.

combining identical amps is fine, not too hard, but i would stay away from using two different amps for one sub. The risk is just too high in my eyes.


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Hell hath no fury like a pissed off balloon animal.

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I'm getting the impression that I'm pissing people off. This is not my intention, I'm simply trying to learn as much as I can, and the best way to do that is to put up what I know and see what I'm wrong at and what I'm right at.


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Hell hath no fury like a pissed off balloon animal.

"Sup, G?"
"Aren't you white?"
"Only on the outside, craka."

Bloodspiller wrote:I'm getting the impression that I'm pissing people off. This is not my intention, I'm simply trying to learn as much as I can, and the best way to do that is to put up what I know and see what I'm wrong at and what I'm right at.

why would you think that?

Anyways so i guess its certain that i cant do this. Thanks for letting me no!


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84 Fiero

the only PROPER and good way to do it is to use a scope to set the amps PERFECTLY..if they aren't exactly the same, each coil on the sub will be getting a different signal...resulting in a dead woofer.

There are amps that are made for this sorta thing...they have a master/slave gain setup which allows you to match the gains without using expensive equipment.

but what do i know.


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Ok so if i run it off of mu 800 watt amp i should be good though? Because i have heard you can mess a sub up if you dont run at least its rms


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84 Fiero

wysiwyg wrote:the only PROPER and good way to do it is to use a scope to set the amps PERFECTLY..if they aren't exactly the same, each coil on the sub will be getting a different signal...resulting in a dead woofer.

There are amps that are made for this sorta thing...they have a master/slave gain setup which allows you to match the gains without using expensive equipment.

but what do i know.

But i was thinking if i take the + from both amps and draw those to one + together and do the same with the negatives then bridge the sub that all the power would go to both coils equally


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84 Fiero

J K (84_Fiero) wrote:

wysiwyg wrote:the only PROPER and good way to do it is to use a scope to set the amps PERFECTLY..if they aren't exactly the same, each coil on the sub will be getting a different signal...resulting in a dead woofer.

There are amps that are made for this sorta thing...they have a master/slave gain setup which allows you to match the gains without using expensive equipment.

but what do i know.

But i was thinking if i take the + from both amps and draw those to one + together and do the same with the negatives then bridge the sub that all the power would go to both coils equally

but the gains on each amp have to match perfectly.


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J K (84_Fiero) wrote:Ok so if i run it off of mu 800 watt amp i should be good though? Because i have heard you can mess a sub up if you dont run at least its rms

Whoever told you that isn't very smart. The sub will run fine off of 800 watts.

Scott Tutty wrote:

J K (84_Fiero) wrote:Ok so if i run it off of mu 800 watt amp i should be good though? Because i have heard you can mess a sub up if you dont run at least its rms

Whoever told you that isn't very smart. The sub will run fine off of 800 watts.

yep...you can run 10 watts to it and be perfectly fine. underpowering a sub doesn't hurt it one bit.


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Not to argue but, underpowering a sub can and will destroy a sub.. BUT! The only time i've actually seen it happen, is when a friend played his stereo at the MAX all the time.. He pushed like 75w(maybe even 50w) to two 12's(JL something, w6's,w3's?) He blew them within two weeks of buying them brand new.. Of course the gain was maxed, aswell as the bass boost, clipping the @!#$ outta the amp.. Don't improvise headunit folume for a lack of real power..

In this situation though, 800w will be just fine with that 10.. I'd use the Sony amp for the rest of the speakers..



"If life throws you a curve, pop the clutch and drift it!"

^^your friend killed his sub with distortion...not due to the fact it was underpowering.

this is a fact...underpowering does not hurt a sub. don't try to argue it.


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ok..lemme break it down to ya on how it works...

High Power Amp at a high level-
Your Speaker's cone moves enough to cool the coil sufficiently..meaning no burnt coil.

Low power amp at High level
In the case of your friend...he was driving a severely clipped signal to his sub.(probably a full square wave) This means the cone does not move as far as it should to cool the coil properly in proportion to the amount of power it's given.

It's possible when driving a fully clipped signal like that, that your amp can produce up to TWICE as much power as it's rated for...so the power doubles, but the coil does not increase in proportion to the power increase. so you end up with your coil getting distorted or melting, or the adhesive will fail.

so i will tell you again...underpowering does NOT hurt speakers. dirty clipped signals and distortion do.


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J K (84_Fiero) wrote:Ok so if i run it off of mu 800 watt amp i should be good though? Because i have heard you can mess a sub up if you dont run at least its rms

if underpowering was bad for the speakers, then i would never turn my volume down.

schembo2000 wrote:

J K (84_Fiero) wrote:Ok so if i run it off of mu 800 watt amp i should be good though? Because i have heard you can mess a sub up if you dont run at least its rms

if underpowering was bad for the speakers, then i would never turn my volume down.

nobobdy seems to realise this schembo. thats how i try to prove to people that underpowering a speaker is completly fine.




start questor, underpowering in no way hurts a speaker whatesoever. your friend blew his sub by running the gain at max, not by underpowering a sub. two copletly diffrent things, underower had nothing to do with it, he could have had an amp feeding the exact rms to the sub, or an amp feeding the max to the sub, and with the gain maxed he would have done the exact same thing, underpowering it, had absolutely nothing to do with it.


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have you checked if the amps or amp runs at 2ohms. if so that would turn your 800 into more. and it does not matter if the amp is 2 channel that means you could just daisy chain the subs termianls together (one wire to the pos and neg and then the other pos to the amp and the other neg to the amp) but i dont anything about that sub so check to see if you can do that.

I've been told that you can actually kill a sub by underpowering it because the power still heats up the coils, but the sub doesn't move enough to circulate the amount of air needed to cool them. Is this a myth, or does it actually happen?


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Hell hath no fury like a pissed off balloon animal.

"Sup, G?"
"Aren't you white?"
"Only on the outside, craka."

if your not even pushing enough wattage to move a sub your not going to be generating much heat. im sure anyone with a 1000 watt sub could run out to their cars, turn the volume to 1 on their dial and see what happens.


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grimy1 wrote:have you checked if the amps or amp runs at 2ohms. if so that would turn your 800 into more. and it does not matter if the amp is 2 channel that means you could just daisy chain the subs termianls together (one wire to the pos and neg and then the other pos to the amp and the other neg to the amp) but i dont anything about that sub so check to see if you can do that.

Isnt that called bridging?


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84 Fiero

Bridging refers to the act of making two amplifier channels function as one. An example is an amplifier that's rated at 100 WPC in stereo that says it will also deliver 200 WPC bridged. Bridging effectively combines both the right and left channels of your amplifier and makes them one mono channel. This is mostly used with subs, because frequencies low enough to require a sub are effectively non-directional so you won't destroy your stereo image by bridging the amp to your sub(s).

Placing the speaker's voice coils (yes the HX2 has two voice coils according to Rockford) in such a fashion that both speaker positives are connected together and both speaker negatives are connected together is called putting the voice coils in parallel. If you've got a sub with two 4 ohm voice coils (and I didn't check the specs on your exact sub, because there are most likely more than one model...with different voice coil specs), and you parallel them, your amp will see a 2 ohm load. Be sure your amp can take that load before wiring your speakers that way or you might cause damage to your amp. If you've got two 8 ohm voice coils parallelled (hope I spelled that right), then your amp will see a 4 ohm load, and I don't know of any car amp that can't handle that.

You had mentioned in an earlier post what sounded to me like you had planned on putting your speaker's voice coils in parallel and then connecting them to the outputs of two amps at the same time. Let me stress that this is not a good idea. Even if the amps are the same, you're likely to cause damage to one or both amps (and who knows what else) by doing this. I may have misunderstood your question in that post, and if I did you can somewhat ignore my statement, but it's just not something I'd recommend. I've installed loads of equipment in lots of cars, and this is something I've never done. I've matched amps so that there are two amps per sub, but they were on dual voice coil subs and were matched amps each with their own voice coil to drive...and that was back when you had to match them properly with the correct equipment, since there were no ganged gains at that point in time.

I certainly don't want to sound like a know-it-all, but I just don't want to see you waste $$ or equipment. Good luck!

Thanks man. Tons of help. Im just getting into car audio so im still learning. excuse me for that. lol Anways yea you got it all exactly the way i was putting it. Im just gonna use the RF amp for it. and do whatever with the sony. running it bridged and parallel.


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84 Fiero

sndsgood wrote:if your not even pushing enough wattage to move a sub your not going to be generating much heat. im sure anyone with a 1000 watt sub could run out to their cars, turn the volume to 1 on their dial and see what happens.

I didn't neccessarily mean so little power the sub doesn't move. I meant enough to heat the coils, but not enough to get the excursion/air movement it needs.


______________________________________
Hell hath no fury like a pissed off balloon animal.

"Sup, G?"
"Aren't you white?"
"Only on the outside, craka."

dude, as long as the speaker is not distorting, underpowering the speaker won't hurt it. Period.